Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of general common knowledge in the field.
It is known to fabricate structural parts for buildings, tanks or the like from concrete using modular stay-in-place formworks. Such structural parts may include walls, ceilings or the like. Examples of such modular stay in place formworks include those described US patent publication No. 2005/0016103 (Piccone) and PCT publication No. WO96/07799 (Sterling). A representative drawing depicting a partial formwork 28 according to one prior art system is shown in top plan view in FIG. 1. Formwork 28 includes a plurality of wall panels 30 (e.g. 30A, 30B, 30D), each of which has an inwardly facing surface 31A and an outwardly facing surface 31B. Each of panels 30 includes a terminal male T-connector component 34 at one of its transverse, vertically-extending edges (vertical being the direction into and out of the FIG. 1 page) and a terminal female C-connector component 32 at its opposing vertical edge. Male T-connector components 34 slide vertically into the receptacles of female C-connector components 32 to join edge-adjacent panels 30 and to thereby provide a pair of substantially parallel wall segments (generally indicated at 27, 29). Depending on the needs for particular wall segments 27, 29, different panels 30 may have different transverse dimensions. For example, comparing panels 30A and 30B, it can be seen that panel 30A has approximately ¼ of the transverse length of panel 30B.
Formwork 28 includes support panels 36A which extend between, and connect to each of, wall segments 27, 29 at transversely spaced apart locations. Support panels 36A include male T-connector components 42 slidably received in the receptacles of female C-connector components 38 which extend inwardly from inwardly facing surfaces 31A or from female C-connector components 32. Formwork 28 comprises tensioning panels 40 which extend between panels 30 and support panels 36A at various locations within formwork 28. Tensioning panels 40 include male T-connector components 46 received in the receptacles of female C-connector components 38.
In use, formwork 28 is assembled by slidable connection of the various male T-connector components 34, 42, 46 in the receptacles of the various female C-connectors 32, 38. Liquid concrete is then poured into formwork 28 between wall segments 27, 29. The concrete flows through apertures (not shown) in support panels 36 and tensioning panels 40 to fill the inward portion of formwork 28 (i.e. between wall segments 27, 29). When the concrete solidifies, the concrete (together with formwork 28) may provide a structural component (e.g. a wall) for a building or other structure.
A known problem with prior art systems is referred to colloquially as “unzipping”. Unzipping refers to the separation of connector components from one another due to the weight and/or outward pressure generated by liquid concrete when it is poured into formwork 28. By way of example, unzipping may occur at connector components 32, 34 between panels 30. FIG. 2 schematically depicts the unzipping of a prior art connection 50 between male T-connector component 34 and corresponding female C-connector component 32 at the edges of a pair of edge-adjacent panels 30. The concrete (not explicitly shown) on the inside 51 of connection 50 exerts outward forces on panels 50 (as shown at arrows 52, 54). These outward forces tend to cause deformation of the connector components 32, 34. In the FIG. 2 example illustration, connector components 32, 34 exhibit deformation in the region of reference numerals 56, 58, 60, 62, 64, 68. This deformation of connector components 32, 34 may be referred to as unzipping.
Unzipping of connector components can lead to a number of problems. In addition to the unattractive appearance of unzipped connector components, unzipping can lead to separation of male connector components 34 from female connector components 32. To counteract this problem, prior art systems typically incorporate support panels 36A and tensioning panels 40, as described above. However, support panels 36A and tensioning panels 40 may not completely eliminate the unzipping problem. Notwithstanding the presence of support panels 36A and tensioning panels 40, in cases where male connector components 34 do not separate completely from female connector components 32, unzipping of connector components 32, 34 may still lead to the formation of small spaces (e.g. spaces 70, 71) or the like between connector components 32, 34. Such spaces can be difficult to clean and can represent regions for the proliferation of bacteria or other contaminants and can thereby prevent or discourage the use of formwork 28 for particular applications, such as those associated with food storage or handling or other applications requiring sanitary conditions or the like. Such spaces can also permit the leakage of liquids and/or gasses between inside 51 and outside 53 of panels 30. Such leakage can prevent or discourage the use of formwork 28 for applications where it is required that formwork 28 be impermeable to gases or liquids (e.g. to provide the walls of tanks used to store water or other liquids). Such leakage can also lead to unsanitary conditions on the inside of formwork 28 and/or cause or lead to corrosion of reinforcement bars (rebar) used in the concrete structure.
In some applications (e.g. in the walls of tanks used to store water or other fluids), there is a desire to maintain a fluid-tight seal at connections between connector components (e.g. connector components 32, 34). Most prior art systems do not provide fluid-tight seals between connector components. Those prior art systems that do provide fluid tight seals can be difficult to work with because of difficulties associated with making and breaking the fluid-tight connections between connector components (which can be desirable during assembly of a formwork or fabrication of a corresponding structure).
Also, some prior art formwork systems can be difficult to assemble. For example, some prior art formwork systems involve making connections by initially orienting the panels at relatively large angles (e.g. orthogonal angles) relative to one another. Again, this can be difficult or impossible in some constrained spaces.
The foregoing examples of the related art and limitations related thereto are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.
There remains a general need for effective apparatus and methods for modular formwork systems.